Ask moonlighters how they juggle startups with full-time jobs, and you'll hear a common refrain: Say goodbye to free time. Fortunately, that's not their only insight for balancing employment with entrepreneurship. Other lessons learned:

As with any startup, there is no road map for guaranteed success when moonlighting. But a crucial first step is choosing the right business—one that has growth potential but won't jeopardize your full-time job.